Re: How to get non-printing heads?

*To*: mathgroup at smc.vnet.net*Subject*: [mg46998] Re: How to get non-printing heads?*From*: "Peter Pein" <no at spam.no>*Date*: Fri, 19 Mar 2004 01:35:51 -0500 (EST)*References*: <c388k0$bnb$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

"kj" <socyl at 987jk.com> schrieb im Newsbeitrag news:c388k0$bnb$1 at smc.vnet.net... > > How can I give a Mathematica object a different head? > > I tried > > In[1]:= Head[a] ^= Constant; > > But, as shown below, this doesn't work as desired: > > In[2]:= MatchQ[a, _Constant] > > Out[2]= False .... In[1]:= a = Constant["a"]; a^2 + b^2 Out[2]= b^2 + Constant[a]^2 In[3]:= Unprotect[Constant]; Format[Constant[x_String]] ^= x; Protect[Constant]; a^2 + b^2 Out[5]= b^2 + a^2 In[6]:= Head[a] Out[6]= Constant might do what you want -- Peter Pein, Berlin petsie at arcAND.de replace && by || to write to me